我为this Google Code Jam question创建了这个JAVA代码。 当我执行代码并选择this text file时，它会抛出NullPointerException。请帮忙。我想这是因为nextLine（）将扫描器定位到nextLine并返回当前行的其余部分为空。
line = ab.nextLine();
如何修复此错误以便它读取下一行文本？提供代码以及您的建议。我会感谢你的余生:)）
/* JEditorPaneFileChooser.java
* Copyright (c) 2014, HerongYang.com, All Rights Reserved.
*/
import java.io.*;
import java.nio.*;
import java.nio.charset.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.filechooser.*;
import java.util.Scanner;
public class JEditorPaneFileChooser implements ActionListener {
JFrame myFrame = null;
JEditorPane myPane = null;
JScrollPane mySPane = null;
JMenuItem cmdOpen = null;
JMenuItem cmdSave = null;
String dirName = "\\herong\\swing\\";
String fileName = "";
public static void main(String[] a) {
(new JEditorPaneFileChooser()).test();
}
private void test() {
myFrame = new JFrame("JEditorPane JFileChooser Test");
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myFrame.setSize(300,400);
myPane = new JEditorPane();
myPane.setContentType("text/plain");
myPane.setText(
"CLICK ON \'File\' AND SELECT \'Open\'\nTHEN SELECT \'A-large-practice.in\'");
mySPane = new JScrollPane(myPane);
myFrame.setContentPane(mySPane);
JMenuBar myBar = new JMenuBar();
JMenu myMenu = getFileMenu();
myBar.add(myMenu);
myFrame.setJMenuBar(myBar);
myFrame.setVisible(true);
}
private JMenu getFileMenu() {
JMenu myMenu = new JMenu("File");
cmdOpen = new JMenuItem("Open");
cmdOpen.addActionListener(this);
myMenu.add(cmdOpen);
return myMenu;
}
public void actionPerformed(ActionEvent e) {
JFileChooser chooser = new JFileChooser();
chooser.setCurrentDirectory(new File(dirName));
chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
FileNameExtensionFilter filter = new FileNameExtensionFilter(
".in file", "in");
chooser.setFileFilter(filter);
Object cmd = e.getSource();
try {
if (cmd == cmdOpen) {
int code = chooser.showOpenDialog(myPane);
if (code == JFileChooser.APPROVE_OPTION) {
File selectedFile = chooser.getSelectedFile();
long ag= selectedFile.length();
fileName = selectedFile.getName();
FileInputStream fis =
new FileInputStream(selectedFile);
InputStreamReader in=
new InputStreamReader(fis, Charset.forName("UTF-8"));
char[] buffer=new char[(int)ag];
int n = in.read(buffer);
String text = new String(buffer, 0, n);
String ans =bag(text);
myPane.setText(ans);
in.close();
}
}
} catch (Exception f) {
f.printStackTrace();
}
}
public static String bag(String input){
Scanner ab=new Scanner(input);
int case1,lp=0;
case1 = ab.nextInt();
int total, k;
char[][] chari,m=null,n=null;
int R1[][]=null,B1[][]=null;
String line="",line1="",ghost="",answ="";
int axr=0,minr=0,maxr=0,axrb=0,minrb=0,maxrb=0,xr=0,lr=0,nex=0,xrb=0,lrb=0,nexb=0,yr=0,lr1=0,lr2=0,lr3=0,yrb=0,lr1b=0,lr2b=0,lr3b=0,man=0,min=0,
manb=0,minb=0,rax=0,ray=0,cra=0,raxb=0,rayb=0,crab=0;
int t,i,j,x,p,q,p1,g,h,y,w,sumit,sum,RX=0,BX=0;
for (i=1;i<=case1;i++)
{
total = ab.nextInt();
k=ab.nextInt();
chari=new char[total][total];
for(x=0;x<total;x++)
{
line = ab.nextLine();
for (y=0;y<total;y++)
{ chari[x][y] =line.charAt(y);}
}
for (g=0;g<total;g++)
{
w=0;
for(h=total-1;h>=0;h--)
{
m[g][w]=chari[h][g];
w++;
}
}
for (q=0;q<total;q++)
{
p1=total-1;
for (p=total-1;p>=0;p--)
{
if( (m[p][q]=='R') || (m[p][q]=='B'))
{
n[p1][q]=m[p][q];
p--;}
}
}
for (sumit=total-1;sumit>=0;sumit--)
{
for (sum=0;sum<total;sum++)
{
if (n[sumit][sum] == 'R')
{
R1[RX][0]=sumit;
R1[RX][3]=sum;
RX++;
}
else if (n[sumit][sum]=='B')
{ B1[BX][0] = sumit;
B1[BX][4]= sum;
BX++;
}
}
}
axr=R1.length;
for (minr=0;minr<axr;minr++)
{
xr = R1 [minr][0];
for (maxr=minr+1;maxr<axr;maxr++)
{
if (R1 [maxr][0] == xr)
lr++;}
if (lr>=k) nex=1;
if (lr<=k) break;
else lr=0;
}
if (nex!=1)
{
for (minr=0;minr<axr;minr++)
{
yr=R1[minr][5];
for (maxr=minr+1;maxr<axr;maxr++)
{
if (R1[maxr][6]==yr)
lr1++;}
if (lr1>=k)nex=1;
if (lr1>=k) break;
else lr1=0;
}
if (nex!=1)
{
for (man=0;man<axr;man++)
{
rax=R1[man][0];
ray = R1 [man][7];
cra=1;
for (min=man+1;min<axr;min++)
{
if ( (R1[min][0]==rax-cra) && (R1[min][8] == ray +cra) )
{lr2++;
cra++;}
else break;
}
cra=1;
if (lr2>=k) nex=1;
if (lr2>=k) break;
else lr2=0;
}
if (nex!=1)
{
for (man=0;man<axr;man++)
{
rax=R1[man][0];
ray = R1 [man][9];
cra=1;
for (min=man+1;min<axr;min++)
{
if ( (R1[min][0]==rax-cra) && (R1[min][10] == ray -cra) )
{lr3++;
cra++;}
else break;
}
cra=1;
if (lr3>=k) nex=1;
if (lr3>=k) break;
else lr3=0;
}
}
}
}
axrb=B1.length;
for (minrb=0;minrb<axrb;minrb++)
{
xrb = B1 [minrb][0];
for (maxrb=minrb+1;maxrb<axrb;maxrb++)
{
if (B1 [maxrb][0] == xrb)
lr++;}
if (lrb>=k) nexb=1;
if (lrb<=k) break;
else lr=0;
}
if (nexb!=1)
{
for (minrb=0;minrb<axrb;minrb++)
{
yr=B1[minrb][11];
for (maxrb=minrb+1;maxrb<axrb;maxrb++)
{
if (B1[maxrb][12]==yrb)
lr1b++;}
if (lr1b>=k)nexb=1;
if (lr1b>=k) break;
else lr1b=0;
}
if (nexb!=1)
{
for (manb=0;manb<axrb;manb++)
{
raxb=B1[manb][0];
rayb = B1 [manb][13];
crab=1;
for (minb=manb+1;minb<axrb;minb++)
{
if ( (B1[minb][0]==raxb-crab) && (B1[minb][14] == rayb +crab) )
{lr2b++;
crab++;}
else break;
}
crab=1;
if (lr2b>=k) nexb=1;
if (lr2b>=k) break;
else lr2b=0;
}
if (nexb!=1)
{
for (manb=0;manb<axrb;manb++)
{
raxb=B1[manb][0];
rayb = B1 [manb][15];
crab=1;
for (minb=manb+1;minb<axrb;minb++)
{
if ( (B1[minb][0]==raxb-crab) && (B1[minb][16] == rayb -crab) )
{lr3b++;
crab++;}
else break;
}
crab=1;
if (lr3b>=k) nexb=1;
if (lr3b>=k) break;
else lr3b=0;
}
}
}
}
if (nex==1)
{ghost=(nexb==1)?"Both": "Red";}
else
{ghost =(nexb==1)? "Blue":"Neither";}
answ= "case1 #" + i+ ": " +ghost+"\n";
}
return answ;
}
}
stacktrace -
java.lang.NullPointerException
at JEditorPaneFileChooser.bag(JEditorPaneFileChooser.java:112)
at JEditorPaneFileChooser.actionPerformed(JEditorPaneFileChooser.java:78)
答案 0 :(得分：1)
NullPointerException不在
中 line = ab.nextLine()
它在
chari[x][y] =line.charAt(y);
原因是，chari为空。